1. Technical Field
The present invention relates in general to the field of medical lancet devices and self-contained single use lancing devices that enable user safety and security. More particularly, the invention relates to lancing devices containing the lancet needle permanently affixed within the lancing device, providing a safety guard to prevent unintended activation and release of the lancet needle, and providing an indicator within the unit for identifying whether or not the lancing device has been previously activated, used and spent. Additionally, the invention relates to providing a method of indicating and assuring that lancing devices are limited to one-time use only. Specifically, the invention provides a method for indicating whether the lancing device has been activated and the lancet needle ejected from the device and then retracted.
2. Description of the Related Art
Lancets and their uses are well known in the art as a convenient and safe means for piercing or pricking a person's skin to draw small amounts blood that can then be subjected to a variety of medical tests such as for blood sugar content. Typical integrated lancet assemblies are described in U.S. Pat. Nos. 5,439,473 and 6,258,112 and depict a lancet encased within a rectangular-shaped plastic casing. The lancet contains a needle tip and is mounted in the casing in a manner that, through the use of a spring, enables the lancet to be retracted, actively released by the user, and consequently propelled linearly toward one end of the casing. Upon reaching the end of the casing, the needle tip of the lancet extends through a small opening in the casing thereby exposing the needle tip for the purpose of puncturing human skin, such as a fingertip, positioned adjacent to the opening. The spring and lancet are released by pressing on a button or tab. Following activation and extension of the needle tip through the casing opening, the natural state of the spring causes the lancet to partially retract towards its previous state, with the spring and lancet at rest such that the needle tip no longer extends through the casing opening.
Lancets are designed to draw a relatively minute quantity of blood from capillaries immediately below the surface of the skin and are commonly used by the patients themselves at home as well as by medical professionals in medical offices and hospitals. Lancets are used to prick the patient's skin either by manual penetration or in conjunction with a dynamic (usually spring-driven) mechanical device into which the lancet is permanently installed for single use. In the home setting, single use lancing devices are used by the patient and then discarded. These devices are also used in medical office and hospital settings in order avoid the necessity of having to re-sterilize the mechanical device and/or lancet after each use. Other types of lancing devices enable the user to insert, remove and replace lancets after each use. The lancing device is reusable and the lancets themselves are discarded. Single use lancets provide the convenience of enabling the user to discard the entire device and not touch, contaminate or otherwise expose the lancet or inside of the device in a manner that may comprise sterility.
Singe use lancing devices are specifically designed to safely accommodate their purpose as “pricking” devices that are commonly utilized by non-medically trained individuals including children. Specifically, in order to effectuate a safe and controlled puncturing of a patient's skin, the exposed tip of the needle extends only a very short distance (typically a few millimeters) from the flat upper surface of the lancet body, which acts as a bearing to limit the puncture depth. The needle may extend from the upper surface using any well-known lancet configurations, such as by having the needle protrude outward from the lancet body or by otherwise affixing the needle to the upper surface. Together, these signature structural and dimensional characteristics of lancet design give rise to another nearly universal lancet design feature, namely, a single unitary molded plastic device that may be fired once for releasing the lancet needle and pricking the patient's skin surface. After use, the needle remains stored within the casing. The unit may be re-cocked and re-used by using a key to re-compress the spring.
A problem arises, however, concerning safety after a lancing device has been used to draw blood. After the device has been used to prick the patient's skin, the sharp lancet tip is contaminated with the patient's blood. The outer surface of the unit makes contact with the patient's skin and may also be contaminated. Additionally, the needle, retracted back within the unit after use, contains blood that may contaminate the interior of the unit. As with any instrument or device that has been exposed to blood, a used lancing device constitutes a significant biological hazard that must be handled with care.
However, the nature and shape of the lancing devices presents difficulties relating to a user's ability to identify a used device therefore to distinguish a used from an unused lancing unit. A user may only determine whether the device has been used by depressing the activation switch again. By depressing the switch again, the unit will either: (1) not respond, meaning the unit was previously used and should be discarded; or (2) it will activate and fire the needle, thereby spending the unit without any practical use and requiring that it then be discarded. Thus, there is no simple, efficient and practical method of making this determination in advance of the lancing device's use.
Since lancing devices are commonly stored in bags or boxes of more than fifty, the inability to readily and reliably distinguish between used and unused lancing devices creates significant health and safety problems in which contaminated devices may be used and then replaced into the storage bag among unused devices without the knowledge of the next user. Given the many prevalent blood-borne diseases such as hepatitis, a single such misidentification is potentially catastrophic. Additionally, federal regulations and requirements of the health care industry, such as Medicare, contain provisions that medical and heath providers cannot use or stock returned lancet inventory without definite certainty that the returned items have not been tampered with or used.
It can therefore be appreciated that a need exists for an improved lancing design that overcomes the foregoing problems associated with the inability to determine whether a lancing device is spent.